A biosensor and a method of detecting one or more analytes is disclosed. The biosensor comprising a waveguide for receiving and propagating an optical radiation along the length of the waveguide as a long range surface plasmon-polariton (LRSPP) wave with its transverse electric field substantially perpendicular to the width of the waveguide. The waveguide comprising an input region for receiving the optical radiation at one end; an output region at an opposed end for emitting the propagated optical radiation away from the waveguide and towards a detector; and a sensing region between the input and output region; a dielectric cladding surrounding the waveguide; and at least one fluidic channel formed in the dielectric cladding for moving a fluid towards and away from the sensing region. In some embodiments, the biosensor and methods for analyte detection feature one or more of the following: high detection sensitivity and specificity, scalability and multiplex capacity, ability to simultaneously analyze a plurality of different analytes, and ability to detect or measure multiple individual binding events in real-time.